linux-kernel - Re: [PATCH v3 3/8] x86/sev: Require the RMPREAD instruction after Fam19h

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Message-ID: <ce1f252a-9ef1-4cf1-9d4e-bedab43fd7e1@intel.com>
Date: Mon, 30 Sep 2024 10:03:46 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Tom Lendacky <thomas.lendacky@....com>, linux-kernel@...r.kernel.org,
 x86@...nel.org
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 Michael Roth <michael.roth@....com>, Ashish Kalra <ashish.kalra@....com>
Subject: Re: [PATCH v3 3/8] x86/sev: Require the RMPREAD instruction after
 Fam19h

On 9/30/24 08:22, Tom Lendacky wrote:
>  		if (!cpu_has(c, X86_FEATURE_HYPERVISOR) &&
> -		    c->x86 >= 0x19 && snp_probe_rmptable_info()) {
> +		    (c->x86 == 0x19 || cpu_feature_enabled(X86_FEATURE_RMPREAD)) &&
> +		    snp_probe_rmptable_info()) {

One humble suggestion (and not a NAK of the series): Could we please
start using #define'd names for these family numbers?  We started doing
it for Intel models and I think it's been really successful.  We used to
do greps like:

	grep -r 'x86_model == 0x0f' arch/x86/

But that misses things like '>=' or macros that build the x86_model
comparison.  But now we can do things like:

	grep -r INTEL_CORE2_MEROM arch/x86

which does a much better job of finding references.